My understanding is that blue board is also much stronger than drywall and has better sound deadening properties. Most of the texture in drywall comes from the

My understanding is that blue board is also much stronger than drywall and has better sound deadening properties. Most of the texture in drywall comes from the paint and is intentional to hide imperfections. Joint compound is used at the seams to hide and smooth out imperfections, it's of a different texture than the drywall itself and a truly flat paint job would reveal all the seams. Blue board avoids this by coating the entire surface and joints in a skim coat of plaster.